Incompressible lifting-surface aerodynamics for a rotor-stator combination

Current literature on the three dimensional flow through compressor cascades deals with a row of rotor blades in isolation. Since the distance between the rotor and stator is usually 10 to 20 percent of the blade chord, the aerodynamic interference between them has to be considered for a proper evaluation of the aerothermodynamic performance of the stage. A unified approach to the aerodynamics of the incompressible flow through a stage is presented that uses the lifting surface theory for a compressor cascade of arbitrary camber and thickness distribution. The effects of rotor stator interference are represented as a linear function of the rotor and stator flows separately. The loading distribution on the rotor and stator flows separately. The loading distribution on the rotor and stator blades and the interference factor are determined concurrently through a matrix iteration process

Acoustic pressures emanating from a turbomachine stage

A knowledge of the acoustic energy emission of each blade row of a turbomachine is useful for estimating the overall noise level of the machine and for determining its discrete frequency noise content. Because of the close spacing between the rotor and stator of a compressor stage, the strong aerodynamic interactions between them have to be included in obtaining the resultant flow field. A three dimensional theory for determining the discrete frequency noise content of an axial compressor consisting of a rotor and a stator each with a finite number of blades are outlined. The lifting surface theory and the linearized equation of an ideal, nonsteady compressible fluid motion are used for thin blades of arbitrary cross section. The combined pressure field at a point of the fluid is constructed by linear addition of the rotor and stator solutions together with an interference factor obtained by matching them for net zero vorticity behind the stage

An analysis for the sound field produced by rigid wide cord dual rotation propellers of high solidarity in compressible flow

An unsteady lifting service theory for the counter-rotating propeller is presented using the linearized governing equations for the acceleration potential and representing the blades by a surface distribution of pulsating acoustic dipoles distributed according to a modified Birnbaum series. The Birnbaum series coefficients are determined by satisfying the surface tangency boundary conditions on the front and rear propeller blades. Expressions for the combined acoustic resonance modes of the front prop, the rear prop and the combination are also given

Impact of Physico-Chemical Characteristics on Phytoplankton Diversity of Nalligudda Lake, Bangalore

Physico-chemical parameters of water are a prime consideration to assess the water quality of a lake for its best utilization for drinking, irrigation and fisheries. In the present investigation, the study of monthly variation of different physico-chemical characteristics and phytoplankton diversity were carried out from January to December 2011 to know the water quality of Nalligudda Lake of Bangalore. Physico-chemical parameters of the water samples such as water temperature (24.2-32.3.C), pH (7.1-8.5), total dissolved solids (300-800 mg/L), electrical conductivity (468.75-1250 µmhos/cm), dissolved oxygen (3.9-7.15), biological oxygen demand (2.4-7.2), chemical oxygen demand (9.9-41.4), phosphate (0.32-3.1 mg/L) and nitrate (2.86-6.4 mg/L) were recorded in the present investigation. Totally 51 species of phytoplankton belonging to different taxonomic groups were identified. Among these, 22 species belonged to Chlorophyceae, 8 species to Euglenophyceae, 2 species to Chrysophyceae, 2 species to Dinophyceae, 10 species to Bacillariophyceae and 7 species to Cyanophyceae. Chlorophyceae formed the dominant group. Dominance, Shannon index, Simpson index and Evenness of the species were also calculated

Impact of Climate Change on Water Quality of Shoolkere Lake, Bangalore

An attempt has been made to ascertain the water quality of Shoolkere Lake with regard to physico-chemical parameters like temperature, pH, turbidity, Total Dissolved Solids (TDS), Electrical Conductivity (EC), Dissolved Oxygen, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Free CO2, chloride, alkalinity, hardness, phosphate, nitrate, sulphate and iron. Seasonal variations in the water quality parameters were investigated during the monitoring period from January to December 2010. The relationship between various physico-chemical parameters were analyzed statistically by Pearson correlation analysis. The results revealed that the condition of this Lake in different seasons showed fluctuations in physico-chemical parameters. Correlation coefficient showed positive and negative relationships between the physico-chemical parameters and also showed high significant positive relationship (p<0.01 level) and significant positive relationship (p<0.05 level)

Abrasive Water Jet Cutting: A Risk-Free Technology for Machining Mg-Based Materials

Mg-based materials are considered to be the most machinable of all materials due to their good machinability. Though conventional machining of Mg-based materials is a topic that has been widely discussed, they are associated with ignition issues. Ignition risk in conventional machining of Mg-based materials thus cannot be denied and should be avoided. Literature has witnessed ignition risk when machining temperature reaches above 450°C during turning and milling processes, and some cases are reported with fire hazard. In order to obtain the safest machining atmosphere, abrasive water jet machining, a most desired machining technology for machining Mg-based materials, is discussed in the present chapter. The text covers ignition risk in conventional machining of Mg-based materials, an overview of non-traditional methods for machining Mg-based materials, advantages of abrasive water jet machining over other methods, abrasive water jet linear cutting of Mg alloys and composites, and drilling of Mg alloys. Experimental investigations are carried out to know the effect of abrasive water jet process parameters on machining Mg alloys and Mg nanocomposites. Surface topography of cut surfaces is analyzed. Suitability of abrasive water jet in drilling Mg alloys is justified by comparing results with holes drilled by conventional drilling and jig boring

Studies on Population Dynamics and Seasonal Abundance of Zooplankton Community in Doddavoderahallilake, Bangalore

The present study was undertaken to investigate the zooplankton diversity in Doddavoderahallilake through different months during the period of January 2010 to December 2010. The sample consists of moderate biodiversity of total zooplankton with 15 species belonging to four taxonomic groups. Out of 15 species 9 belonged to Rotifera, 4 to copepod, 1 to cladocera, and 1 to Ostracoda. Rotiferan species have showed a high magnitude of biodiversity in comparative to other zooplankton subgroups. The percentage dominance of Rotifers were 45.05%. The values of number of zooplankton species indicating the pattern of bio diversity have exhibited a different dominating trend of its major subgroups as given rotifera>copepoda>cladocera>Ostracoda. The present study aims at providing a preliminary knowledge on the productivity and diversity of zooplanktons which can be utilized during the formulation of management measures to improve the productivity of the lake